The present invention concerns a method for the cleaning and sterilizing of a filler pipe on a packing machine of the type which manufactures a continuous series of mutually connected packing containers from a web of packing material which containers, while in connection with one another, are filled with contents via the said filler pipe, to be subsequently separated from one another to form individual packing containers. The invention also concerns an arrangement for the realization of the method.
Packing machines for the packaging of milk or other liquid dairy products in disposable packages are known. A number of these machines manufacture filled packing containers by the continuous forming of one or more webs of packing material into individual packages. The forming usually takes place in a manner such that the packing web material or the webs are successively converted to liquid-tight packages, which, however, are not separated from one another, but hang together, so that a more or less tubular material body, consisting of a number of packages, is formed. During the manufacturing process the material moves downwardly through the packing machine and the tube thus grows at its upper end. Through this upper end extends a pipe through which the product, which is to fill the packages, can enter into the packing material tube. Inside the packing material tube the pipe passes over into the filler pipe proper which extends concentrically downwardly through the packing material tube and during the production of the packages continuously supplies contents in such a quantity that the packing containers located at the bottom end of the tube are filled to the required extent. When a package, which at a certain instant forms the lowest part of the tube, has been filled with contents to the required extent, it is separated from the series of packages or the tube located above by means of a pressing together of the tube walls in a transverse zone. Subsequently a sealing together of the compressed tube walls takes place. The finished package is separated from the packing material tube following a cutting through the sealing zone.
In the packing machines of the above-mentioned type, as in all machines for the packaging of foodstuffs, high standards of hygiene must be maintained. Thus it must be possible to clean and sterilize in a simple and effective manner the parts of the machine which come into direct contact with this contents. This is facilitated in that the type of machine has only a small number of parts which come into direct contact with the contents, namely the filler pipe itself, through which the contents flow and the outside of which is surrounded by the contents located in the lower part of the material tube, and any liquid level detector located in the material tube. In the normal operation of the packing machine these parts are dismantled and cleaned before each prolonged interruption of production, such as, for example, every evening. After dismantling, a washing of the parts by hand takes place, whereupon they are assembled again in the machine which is started up and allowed to operate for a short while without any supply of contents, so that an empty material tube is formed which covers and protects the cleaned parts of the machine.
Before the machine is to be restarted for production, a sterilization of the parts coming into contact with the contents takes place wherein a sterilizing agent, e.g. superheated steam, is sprayed through the feed pipe and into the empty material tube, via the upper, open part. The machine is then ready for production.
Another known manner for the cleaning of the filler pipe exists wherein of the pipe is washed in situ in the machine, a cleaning agent, e.g. 2% caustic soda, being allowed to flow through the feed pipe in place of the contents and out into the tube in the same manner as described above for the sterilizing agent. The resistance and durability of the tube material, however, limit the permissible time of flow of the cleaning agent through the pipe and an optimum cleaning result cannot be obtained in this manner, so that cleaning by hand is preferred. However, cleaning by hand is also difficult, since the filler pipe is generally very long and frequently has a flattened section or tapers strongly towards the orifice end.
In packing machines which manufacture aseptic packages, that is to say packages with sterile contents, the hygiene standards are moreover so high that safety is jeopardized through the manual reassembly of the filler pipe in its place in the machine, necessarily after the washing by hand of the same.